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Coloured scanning electron micrograph (SEM) of Northern black widow spider, male (Latrodectus variolus). This venomous spider is found throughout the eastern US, from southern Canada to Florida, and west to eastern Texas. The male (seen in this image) is distinctive since it possesses large anterior head palps that are used for transferring sperm packets to the female. The female black widow is dangerous to humans, as her bite contains a significant amount of nerve toxin (neurotoxin, latrotoxin). This neurotoxin causes pain and swelling, and in rare cases, may even be fatal. The genus gets its name from the female's practice of devouring the male after mating, although this behaviour is seen in other spiders. After the female and male mate, the female lays several bunches of egg sacs in the web, each containing about 750 eggs. Magnification: x1.1 when shortest axis printed at 25 millimetres.